1. Field of Invention
The present invention relates to a photosensor device, especially a photosensor device for determining incident light.
2. Description of Related Art
Due to low manufacturing cost and easy application, silicon photodiodes and phototransistors are often used to sense surrounding light, as ambient light sensors. Silicon photodiodes and phototransistors are also often integrated in integrated circuits.
However, for a silicon-based photosensor to sense and distinguish images for different environments, an optical filter (such as IR pass filter or IR filter) is usually required. This is because: the silicon-based photosensor has a much wider sensible range than human eyes with respect to wavelengths. The silicon-base photosensor can sense not only visible light but also infrared light, and therefore there are more noises. If the silicon-based photosensor is used to sense visible light in a normal environment, because it also receives infrared light, there are noises in the sensed image. On the other hand, if the silicon-based photosensor is used to sense infrared light, although the silicon-based photosensor may be in a dark environment, because the silicon-based photosensor also can sense visible light, the image sensed by the silicon-base photosensor has a high noise ratio due to the retrieved visible light.